We present an all-optical technique that permits sorting within a polydisperse sample of microparticles in the absence of any microfluidic flow. We can sort colloidal samples based on their size and their refractive index. We show experimental and theoretical data for this method. It is based on the specific response of different microparticles to an interference pattern of fringes vibrating with an asymmetric time modulation. The size selectivity arises from the spatial fringe periodicity whereas selection based on refractive index is controlled by the beam power.

We present a device for measuring displacement based on the Talbot and the nonsteady photo-electromotive force effects. The proposed device does not require any numerical signal processing since its output signal is, in appropriate regions, linearly related to the measured displacement. The proposed system requires an illuminating field with a sinusoidal amplitude distribution and low fringe visibility. The dynamic range can be adjusted according to the illuminating field spatial period or wavelength. Displacements with an estimated resolution better than 10 μm in a dynamic range of 1.5 mm were detected using a sinusoidal amplitude grating with a period d=100 μm.

We describe an adaptive interferometer based on rubidium vapor, which combines a good signal-to-noise ratio with a high cutoff frequency of approximately 1 MHz. These features can be useful for optical detection of ultrasound generated in diffusely scattering objects in the presence of strong environmentally produced vibrations.

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We use an adaptive photodetector for measuring the visibility of the Fresnel diffraction patterns generated by a grating. Visibility is measured in real time, with high spatial resolution, and without any signal processing. This method is well suited for analyzing the Talbot effect and its many applications.